If you are looking for a perfect, quick and foolproof way to cook flat iron steak in cast iron, look no further. This method is easy to follow, quick to cook and super delicious!

Oh yeah, AND it's melt-in-your-mouth heaven.

How do you like your steak cooked?

Do you like your steak rare, medium-rare, medium or well done? Think about how you like your steak cooked BEFORE you start cooking. The more well-done you like your steak, the longer you'll need to sear the steak.

Gather together

1 flat iron steak (about 1.25 pounds)

Fresh Rosemary

Kosher Salt (or fine salt)

Finishing Salt (or a course salt)

Black Pepper (fresh ground)

Olive Oil

Cast Iron Griddle Pan (affiliate link) or a 12" cast iron pan

Tongs

Prepare to cook

Each one of these steps is essential to cooking the perfect flat iron steak in cast iron. Don't worry, it's easy, you can do it! Just follow the simple steps listed below:

Step 1 - Dry

Dry the meat with a clean paper towel. Be sure to soak up all of the juices. Drying the meat will ensure the steak will have a crunchy exterior. If you don't dry the steak, you could end up boiling the steak. Then, it would be hard to get the crunchy exterior without overcooking the meat.

Step 2 - Season + Marinate

Flavoring the meat is such an important step. You will need more seasoning (salt) than you think! You will want to marinate a flat iron steak for about 30-60 minutes before cooking.

Marinate your steak does not have to mean soaking it in a liquid of sorts. Remember, you want your steak dry when you cook it. Well, I actually marinate my steaks in a little oil...but oil will sear when it hits the hot skillet.

A simple and flavorful marinade for flat iron steak:

2 Tsp of fine kosher salt (1 tsp per side, evenly sprinkled) The kosher or (fine) salt will season the entire steak through to the center. Kosher salt is important for big flavor.

1 Tsp of finishing salt (½ tsp per side, evenly sprinkled). Optional. I love using a course salt or finishing salt in conjunction with kosher salt. The course salt can't penetrate the steak like the kosher salt, but it does add more flavor and elevates the crunch and flavor in the crust.

1-2 Tsp Fresh Cracked Black Pepper (½ - 1 tsp per side, evenly sprinkled). The amount of pepper you use is up to you. I happen to love lots of pepper for a spicier crust.

3 Tbsp Chopped Fresh Rosemary (1-½ tbsp per side, evenly sprinkled). Optional. Fresh rosemary is great for flat iron steak in cast iron because rosemary handles the char flavor well. Delicate herbs, shallot and garlic can burn, leaving an acrid or bitter taste in your mouth.

2 Tbsp Oil (1 tbsp per side) This will help to give the steak a nice crust. It's best to use an oil that is good for high heat cooking. Light olive oil, canola oil and sunflower oil are good choices. I'll be honest, I've used extra virgin olive oil before, and it turns of just delicious, even though it is best used with low heat or as a finishing oil.

Step 3 - Bring to room temperature

After you season + marinate the steak, allow it to come to room temperature before cooking (30-60 minutes). You do this so that it cooks evenly and doesn't shock the meat. If you cook the steak when its cold, you may need to cook the steak longer to heat it all the way through. And your steak could end up tough.

Season the steak, pour yourself a glass of wine and unwind. When that glass is empty, the steak is ready to cook!

Cook

Step 4 - Preheat the skillet (make sure it's hot)

This is so important. If the skillet isn't 100 percent hot when you add the steak, it will cook unevenly and you won't end up with a nice crunchy "bark" on the outside.

Cook the steak on a medium-high heat, and make sure your skillet is at that temperature before you add the steak.

Step 5 - Sear + Let it Be

Add the steak to the skillet and let it be. Don't push or press down on the steak. This is another tip to create a nice bark and great grill marks. If you move the steak around, you won't get a nice sear, and you can say good bye to those grill marks. To get a great char, set it and forget it for at least 3 minutes.

Cooking Time

(Cooking times are approximate and only a guideline for a 1 pound flat iron steak, around 1 inch thick, on medium-high heat.  Please adjust cooking times accordingly.)

Rare: 3 mins per side

Medium-Rare: 3-4 minutes per side

Medium: 4-5 minutes per side

Medium-Well: 5-6 minutes per side

Well-Done: 6-7 minutes per side

How do I cook this steak evenly?

Make sure that your skillet is up to temperature before adding the steak. Then, cook the steak for the same amount of time on both sides.

How do I know when it's done?

There are two ways to know your steak is done: the finger test and using a meat thermometer.

Check out the article on the finger test from The Butcher Boy here.

Thermometer temps:

(Cooking times for a 1 pound flat iron steak, around 1 inch thick, on medium-high heat)

Rare: 120-125 degrees F (3 mins per side) *Do not tent with foil when resting*

Medium-Rare: 135 degrees F (3-4 minutes per side)

Medium: 140 degrees F (4-5 minutes per side)

Medium-Well: 150 degrees F (5-6 minutes per side)

Well-Done: 160-175 degrees F. (6-7 minutes per side)

**The steak's thermal temperature will continue to rise (carryover cooking) after it's removed from the heat source. The internal temperature will continue to rise about 5 degrees while it's resting. Remove the steak from the heat source just under where you want your steak to be.

Step # 6 - Rest

Why do you need to rest steak?

You need to rest your steak because as the steak cooks, the fibers shrink (which is what creates a juicy steak). When you allow time for the steak to rest, the fibers are able to relax, and the juices are redistributed into the fibers again. The juices remain in the steak when cut, they don't end up all over your cutting board.

How to rest.

When the steak is done to your liking, let it rest on a wood cutting board, or a cooking rack for 10 minutes. Again, this will allow the juices to redistribute throughout, giving you a nice tender, juicy steak.

**It is important to rest the steak on a wood cutting board or cooling rack so that the temperature of the steak doesn't drop too quickly. If you cool the steak on a cold plate, the steak temperature could drop faster than desired. Carryover cooking happens during the resting phase and speeding up the process may result in an underdone steak.**

Should I cover with foil while it's resting?

Short answer: no. (But it's completely up to you)

Leave the steak bare and uncovered while it's resting. I say this for 2 reasons:

First, covering the steak (even with a tinfoil tent) will create moisture and that crust you just worked so hard to make could loose it's crunch.

Second, covering with foil will slow the temperature of the meat from dropping. This could be beneficial if you think the steak is slightly undercooked, because it will increase the carryover cooking time. If your steak is on the verge of perfect, be sure to rest it bare (uncovered).

Step # 7 - Slice it up

How to slice

Be sure to slice the steak against the grain. Remember those fibers that hold the juices? To get a tender bite of steak, you'll want to break down those fibers into smaller pieces. If you cut with the grain, you won't be breaking down the fibers into smaller pieces, and your steak with be tough to chew.

Some sides that go well with flat iron steak

Top this steak with some Arugula Chimichurri Sauce and serve with The Best, Crispy Smashed Potatoes, Creamy Polenta or Creamy (dairy-free) Mac and Cheese.

Add some veggies to your meal with Maple Roasted Carrots or Strawberry Spinach Salad.

Use leftovers to make these Steak Sliders for a great appetizer or snack.

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